# Throttling in thermodynamics

1. Dec 25, 2012

### tomz

I am a new starter on thermodynamics, here is my question.How does a throttle work?
I can understand the equation behind throttling process, how enthalpy is conserved...etc
But I cannot understand how throttle actually achieve the decrease in pressure? is it through turbulent the flow?

2. Dec 27, 2012

### 256bits

3. Dec 27, 2012

### Studiot

It isn't the throttle that causes the pressure decrease. The fluid flows from a region of high pressure to a region of low pressure and there expands at constant enthalpy, according to Bernoulli's equation.

Yes, a throttle has a high pressure side and a low pressure side and fluid passes from one to the other through the throttle, but the pressure is set by conditions on each side.

So for instance the high pressure side might be a container of fluid at high pressure that is expanded into a large chamber at lower pressure or even the atmosphere, which maintains the low pressure.
The high pressure may be maintained by the size of the reservoir, or by flow into the reservoir.